Automatic telephone system.



T. e. MARTIN M. JACOBSEN.-

AUTOMATIC TELEPHONE SYSTEM.

A PPLICATION FILEDFEB. 12, I911.

f lllllHi- Patented J an. 28

nrrnn STATES PATENT OFFICE.

TALBOT G. MARTIN,.0F CHICAGO, AND EMIL JACOBSEN, OF EVANSTON, ILLINOIS,

ASSIGNORS TO AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A COR- PORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Jan. 28, 1919.

Application filed February 12, 1917. Serial No. 147,989.

' To all whom it may concern:

Beit known that we, TALBOT G. MARTIN and Emu. JACOBSEN, both citizens of the United States of America, and residents, re-

spectivel of Chicago, Cook county, Illinois, an Evaiiston, Cook county, Illinois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

ringing apparatus is out of proportion to the cost of the remainder of the exchange equipment, and we have designed, therefore,'a ringing system in which each connector is provided with a pole changing or reversing relay in lieu of the usual ringing and ring cut-ofi' relays. When connection is established with a called line, the pole changing relay of the connector in use responds to an extra digit in the called :telephone number to rapidly reverse the connections of the called line to the battery supply relay, whereby an alternating current is produced in the called line to actuate the signal in bridge thereof. Additional novelty is believed to exist in certain other features of the connector circuit, including a new method of accomplishing the change over, from primary' to secondary movement, all of which will be described and ex lained fully hereinafter, reference being ha to the accompanying drawing? In the drawing we have shown diagrammatically private branch exchange equipment embodying our invention, through the medium of which a complete connection has been established between a. calling substation A and a called substation A. The upparatus included in the connection comprises the individual line switch C and the conncctor switch E. The line switch C is associated with the line of the called substation A, while the master switch D is provided forthe purpose of controlling the trunk selecting operations of the line switches (l and C and other similar line switches.

The substation A may be of any approved Our invention relates in general to auto- 'tion A and the line switch (1.

automatic type such, for example, as the substatlon shown in British patent to Martin,

No. 1,419 of 1910. -As represented herein it comprises essentially the receiver 2, transmitter 3, switch-hook 4, ringer 5, and'oondenser 6. 'Being an automatic substation, it is also provided with a pair of impulse springs 7 and 8 controlled by animpulse wheel 9 through the medium of a finger hole dial -(not shown).

The line conductors 12 and 13 of the substation A are connected at the exchange to the individual line switch 0 which is of the general type of line switch disclosed in the British patent to James, No. 26,301 of 1906; being, however, of the particular type shown in U. S. Letters Patent No. 1,078,690, granted Jan. 17, 1912, i to Frank Ncwforth. Through the medium of line switch (7 the line of substation A when calling is given access to a plurality of trunk lines extending to connector switches.

The line switches shown and a plurality of similar switches are controlled in their trunk selecting operations by means of the master switch D. This hitter is of the general type of master switch disclosed'in the above mentioned British patent to James, No. 26,301 of 1906; being, howcyer, more nearly of the particular type disclosed in the British patent to Martin, No. 1,419 of 1910, alsc previously referred to. As is well known, the function of the master switch is to maintain the plnngeis of all idle line switches which it controls in position before the terminals of. an idle trunk line.

One of the trunk lines to which the line switch has access is shown in the drawing as extending to the connector switch E. The connector E is in general similar in construction to the switch shown in'll. S. Letters latentNo. 815,176, granted March 13, 1900, to hcith. l lrirkson, and Erickson, except that the side switch and private magnet are omitted, and the circuits are revised in accordance with the two-wire system of control. Further mmlifications in the circuits,

provided in accordance with our invention, will be dcsrribcd in detail hereinafter.

The substation A and the line switch may be in all respects similar to the Slll)Slll- There has been shown throughout the drawing a pluralityof batteries, B, B etc,

but it is to be understood that there is preferably but one battery'having its positive pole grounded. The reference character S- indicatesv a busy signaling machine, which may 'be' of the usual type common in other automaticsystems ,I

The operation of the system is as follows:

, When the subscriber at substation A removes his receiver to initiate the: call an energizing circuit is completed over the line conductors {12 and 13 for the line relay 14:

- of theline switch .C. Upon attractin its iarmature;theprline relay 1i cldses a 01 cult for the pull-iii winding 18. -.Upon energizin the pull-1n winding energizes its core 511 'ciently td operate both the plunger arm.

Iii-and the cilt-ofi' armature 16; the former rprou h the medium of its plunger (not is own) forcing the bank springs 2225, inclhsive, intd engagement, respectively, with ,contac'ts "2(l29, inclusive; and the latter disconnecting the line conductors 12 and 13 from groundfandbattery', respectively. by the engagement ofi bank springs 22 and 25 with their associated bank contacts 26 and 29, the line conductors 12 and 13 are exture, conductor 58, contact 27, bank spring,

, 23, and the holdingwinding 17 tobattery B, Sincethe line relay 14 is slow acting it retains itsarmature to maintain the pull-in windingenergized until after the above holding circuit has been establishedn A branch of the holding circuit extends byway of con- "ductor 19 to multiple ftest contacts inthe Vance the lungers of all the remaining idle line switc es into position before the ter banks of connector switches having access to the line of substation A, where by a ground potentialon thesetest contacts the said line is made busy. By the engagement ofban'k spring 24 with contact 28 themaster switch is operated in Well known manner to adminal of the next idle'trunkline.

The foregoing operations have occurred in response totheremoval of thereceimr at substation A. ,Thefcalling subscriber may now proceed to mani liulat'e his calling device in accordance with thegfirst digit of the desired number, thereby & producingjin the usual and wellknownmanner a series of interruptions in theiline circuit. At each interruption the line relay 4O de'elnergizes momentaril y and sendsan impulse of current to the vertical magnet 49 over the following path: Ground at G, armature 51 and its resting contact, armature 52 and its working contact, oif normal springs 54 and 56, winding of low resistance slow acting relay 42, and winding of vertical magnet 49 to battery B In response-to these impulses the vertical magnet operates to raise the switch shaft step by stepuntil the wipers 90, 91, and Q2 arrive at the horizontal level of bank contacts in which are locatedthe terminals of the line of substation A. Relay i2 is energized in series with the vertical magnet and retains its armature during the series of impulses, thereby preventingthe opening of the vertical magnet circuit by the shifting of the off normal springs, which operation occurs as soon as the shaft leaves normal position.

The calling subscriber may now call the units or final digit in the desired number, thereby producing as before a series of interruptions in the line circuit. Now, however, the off normal springs-being in the osition shown in the drawing, and the 're ay. 42 having deenergized, the line relay transmits a series of impulses to the rotary magnet 50 over the following path: Ground at G armature 51 and its resting contact, arInature and its workin contact, ofi' normal springs 54 and 55, armature 53 andits restingcontact, armature 60 and its resting contact, armature 67 and its resting contact, and the winding of rotary magnet 50 to battery B The rotary magnet responds to the impulses of current in the, circuit to rotate the wipers 90, 91, and 92 until theyarrive at bank contacts 93, 94, and 95, which form the terminal of the lineof substation A in the bank of the connector E. It will be noted that a branch of the rotar'y magnet circuit extends through the winding of the slow acting relay it to battery B It follows that relay ll will be energized in paral lel with the rotary magnet during the Totation of the switch, and since it is slow act-q ing, it retains its armatures attracted continuously. By the attraction of the upper armature (H the test wiper191 is connected to the winding of relay 43 as follows: Test" wiper 91, armature 6-.L and itsworking contact, armature 68 and its resting contact, and the windingof relay 43 tobattery B Momentary energizations'ofrelay 43 due to wiper 91 passing over busy contacts (if there be any such in its path), are of no consequence because of the alternative circuit for the rotary magnet way of armature 62 of relay -11 and its working contact.

The switch wipers having been rotated into connect-ion with the desired line, the line of substation, A, the operations now de pend onlwhether 'or notthat line is; busy.

Assuming the line to be idle, the test contact 7 94 will be clear of ground, the rela-y'43'will remain inoperative, and upon the 'deenergia zation of relay 44 the following circuit'will be closed: Grounded conductor 58, armature 59 of relay 43 and its resting cont-act, winding 46 of relay 45. resting contact of armaturetlt and the said armature. test wiper 91. test contact .94 and the holding winding 17 of line switch (j to battery B. Relay 45 and the holdin winding 174 are energized in series, the litter operating the cut-off armature 16 to clear the line of substation-A from battery and ground connections in the line switch. Relay 45, upon-energizing, closes a locking circuit for itself by my of its armature tit'icinner working contact, and winding 4-7 to battery B. At the same time at the outer working contact 'of armature 66,,the conductor 58 is connected directto the test wiper 91. Further results ot theenergization of relay 45 are the closure of the line conductors at armatures and 69, the shifting of the control circuit at armature 67 from the rotary mag net to the pole changing relay 7'2. and the breaking of the previously described test circuit at armature 68.

The required connection has now been established. The signaling of the called subscriber is accomplished in the following manner: Each telephone number may have an extrafinal digit, preferably the digit 0, in addition to the ones necessary to control the line selection. When the calling subscriber dials this last digit, the line relay -10 transmits a series of ten impulses to the relay 72 over the following path: Ground at G armature 51 and its restin contact. armature and its working contact. otf normal springs 54 and 55, armature 53 and its resting contact, resting contact of armature 60 and the said armature, armature ($7 and its working contact. armature 74 and its resting contact. and the winding of relay T2 to battery B. The eti'ect of the rapid energizations and decncrgizations of relay 7; rcsponsiveto the impulses is obvious. At, each energization the called line conductors are reversed, as regards their connections to the windings of the bridged battery supply relay 73; and as a result of these reversals the condenser 106 at the called substation is rapidly charged and discharged, first inone direction and then in the other, whereby a, flow of alternating current is produced whichactuates the ringer 105.

preferably of rather high resistance and the relay 73 is given a stilt adjustment so that it will not respond to the comparatively small quantities of current. intermittently supplied to the called line during the signaling operation.

When the subscriber at substation A removes his receiver to answer the call, a direct current circuit is completed over the heavy line "conductors for the two windings of relay 73 in series with battery B, and the said relay is energized. At the rear contact Ringer 105- of armature. T4 the circuit of relay 7; is broken so that it cannot be energized by another operation ot' the dial. The two subscribers are now connected for cmivcrsation.

"Talking battery for the transmitter at subcircuit of release relay 41 which upon dc.-

energizing in turn removes ground from the holding ircuit extending back to line switch and also closes a circuit for the release magnet 48. By the former operation the line switch is allowed to rcstorc to normal by witlnlraning its plunger from the bank,

while th'c cncrgization of the release magnet. 48 results in the rcstoration of th connector to normal. These operations are well nodcrstood and need no further comment It will now he described briefly how the connector ll operates whcn it is attempted to establish conncction with a lly line. For this purpose it will be assumed that the line of substation A was busy when called, in which case the tcst contact tl-l would have a ground potential upon it. l ndcr these circumstaiwcs. when the connector wipers are rotated into,cngagclncnt with the contacts as. M. and 95. the relay it being cncr gizcdduring the rotation as prcriouslv dcscribcd. as soon as the test wiper ill arrives at test contact i l the relay l3 will be cncr gizcd over a circuit already traced with 1-5- sults which will now be pointed out. At the. resting contact of armature 5!) the coinluctor as is disconnected from the winding 46 of relay t5. and at the making contact of the same :HHhltlll't a locking circuit is prepared which. upon the det ncrgization of relay -l-l, is completed over the following path: grounded conductor 58, armature 5!) and its working contact. contact and the contact spring in cngagcmcnt thcrcwith. armature as and its resting contact, and the winding of relay 43 to battery It. ltclay 43 is thus locked in cncrgizcd position until the con ncctor isrclcascd, and the. relay 45 is prevented t'ro'm energizing to establish connection with the called linc. Further results of the operation of relay 43 at this time. are. the opening ot-thc rotary magnet circuit at. the resting contact of armature (it), and the, connection of a lead from the busy signaling machine S to the lower heavy linc conductor at armature (31. By the transmission of a distinctive tone to' the calling subscriber, he

consider to be new and desire to have protected by Letters Patent will be in theappended claims. y I

. What we claim as our invention is:

pointed out LI'n a telephone system, subscribers lines, an automatic switch controllable over a calling line to establish connection with a called line, a source of direct current,and a pole changing relay in said connector operable intermittently'to set up a flow of alternating current from said source over the called line for signaling purposes, means controlledby the response of the called subscriber for rendering said pole changing relay inoperative.

2. In a telephone system, subscribers lines, an automatic switch controllable over a calling line to establish connection with a called line, a'source of direct current, connections from said source to the opposite sides of a connected called line, including a battery supply relay, another relay for reversing said connections, and means controlled by the subscriber on the calling line for rapidly energizing and deenergizing said other relay.

3. In atelcphone system, a calling and a called line, a source of direct current at the exchange, an automatic switch controllable over. the calling line to connect with the called line and to bridge said source across the two conductors thereof, a pole changing relay in said connector for reversing the connections of said source to said line, and means controlled over the calling line for rapidly energizing and denergizing said relay to set -up a flow of alternating current over the called line, means controlled by the response of the called subscriber for rendering said pole changing relay inoperative.

4. -In a telephone. system, a calling and a called line, an automatic connector switch, means comprising .a motor magnet responsive to "a series of impulses in the calling line for operating said switch to connect with the called line, a ole changer in said switch responsive to a su sequent seritas of impulses to set up a flow of alternating current in the called line, and means controlled by the response of the calledsubscriber for render:

' ing said pole changer inoperative.

.5. In a telephone system, a calling and a called line, an automatic connector switch,

primary and secondary motor magnets responsive to successive series of impulses in the calling lineto operatefsaid switch to connect with the called line, a source of dircct current, and apolechanger In .sa d

switch responsive to a subsequent series of impulses to set up a flow of alternatin .cur-

rent in the called line, means controlled by the response of the called subscriber for rendering said pole changer inoperative.

6.'1n a telephone system, acalli'nganda.

called line, an automatic switch comprising talking conductors for connecting said lines,

.aLbattery, a relay bridged across said con talking conductors for connecting said lines, a battery, :1 double wound relay bridged across said conductorsin series with said battery, and means wherebycurrent is supplied from said source through the windings.

of said relay to the connected called'line both for talking and for signaling the called subscriber.

8. In a telephone system, a/ calling and a called line, an automatic switch, means controlled by the calling subscriber for operating said switch to connect with. the called talking and forsignaling the called subline, a relay in the switch for supplying.

talking current to the called line, another relay controlled by the calling subscriber for reversing the connection of said first relay to the called line ,to operate asignal thereat, said first relay controlled by the subscriber on the called line to render said second relay inoperative.

9. In a telephone syste|n, a calling and a called line, an automatic sw1tcl1,.means controlled by the calling subscriber for operating said switch to connect witlnthe calledline, a. relay in the switch for supplying talking current to the called line, another relay controlled by the calling subscriber ,for alternately reversing and restoring the connection of said firsturelay to the called line to operatet a signal thereat. said first relay controlled by the subscriberon the tor called line to render said second relay in-.

operative. I I 10. I In a telephone system, a calling and 0.

called line, an automatic switch, a line relay 1 for said switch, said rtny controlled bythe calling subscriber to operate the switch to connect with the called line, a back bridge reay in the switch for feeding talking curre t to the called line, a relay controlled by said line relay for reversing the connection ofsaid back bridge relay to the called line to'operatea signal thereat, said back bridge relay controlled by the called subcriber to remove said reversing relay from,

the control of the line relay. d

11. In a telephonesystem. a calling. and a called line, an automatic switch, a line relay for said-switch, said relay controlled overtlw 15 .ing signaling and talking 5-.line, a relay controlled by said line relay for reversing, the connections of said hack bridge relay-t0 the called line to operate a signal thereat, said back bridge relay controlled by the called subscriber to remove said revers- 10 ing relay from the control of the line. relay.

12. In a telephone system, a calling and al called line, an automatic switch a relay for said switch in bridge of the calling; line. a back bridge relay in the switch for supplycurrent to the called line, another relay for reversing the connections of said back bridge relay, said first relay controlled over two sides of the line in series in one instance to operate the switclrto connect with the called line and in another instanre to operate said other relay to supply signaling current to the called line. said back bridge relay controlled over theralled line to remove sail other relay from the control of said first relay.

Signed by us at Chicago, Cook county, Illinois, this 6th day of Feb. 1917.

".IALBUL G. MARTIN.

EMI'L JACOBSEN. 

